1. Field of the Invention
The present invention relates to a coding device of moving images based on Motion JPEG-2000, the motion version of the still picture coding standard JPEG-2000, and a coding method of the same.
2. Description of the Related Art
The next generation still picture coding standard JPEG-2000, for which standardization work was completed in January 2001 by the ISO/IEC (International Organization for Standardization/International Electrotechnical Commission), has abundant functions such as a superior compression performance and also scalability, progressiveness, error tolerance, and reversible compression. Thus, it is expected to be widely used in the next generation of digital still cameras, printers, scanners, etc. On the other hand, the motion version of the JPEG-2000, that is, Motion JPEG-2000, inherits the superior features of the JPEG-2000 intact and is expected to find use in future camcoders, monitor cameras, Internet motion picture distribution, remote distribution of medical information, television conference systems, etc.
Motion JPEG-2000, however, deals with a succession of still images of JPEG-2000. With still images, in most cases there is no problem since the images do not move. With moving images, however, there is the problem of a remarkable deterioration in the image quality. Considered a particular problem in the deterioration of the image quality is the flicker noise caused by the occurrence of noise at random positions in a succession of frames.
Flicker noise is caused by, for example, a change in the quantization coefficients in a still region due to the influence of a slight noise component in the original image. In a still region, the quantization coefficients should not change. Despite this, for some reason, noise at the time of taking the picture with a camera etc. will cause noise in the image. The small noise component contained in the image signal will in turn cause the quantization coefficients to change. This will sometimes be detected as flicker noise.